Nanotechnology: An outstanding tool for increasing and better exploitation of microalgae valuable compounds

Abstract

The earth's limited resources demands our society their optimization so that the population's demands for energy, food, water, and medicines are fulfilled. Moreover, the expanding population, along with the socio-demographic shifts, and the emergence of new diseases, comprise the key challenges of this century. It is well-known that worldwide food and energy demands will duplicate by 2050, a scenario that would lead to the overexploitation of existing traditional animal and plant-based resources and cause adverse environmental impacts. Therefore, it is critical that new strategies should be pilared on sustainable production from alternative sustainable and environmentally friendly sources, to meet our society's long-term needs. Within the past decades, microalgae, as unicellular photosynthetic organisms, have attracted significant attention in various fields, from biofuel production to medical fields. Microalgae exhibit very interesting characteristics, such as their faster growth rate and higher biomass efficiency compared to plants. In addition, microalgae contain valuable bioresources, including lipids, pigments, carbohydrates, proteins, and bioactive compounds such as antioxidant, antibacterial, antiviral, anticancer, regenerative, antihypertensive, neuroprotective, and immunostimulating. However, the level of these compounds can be varied under different cultivation conditions such as nutrient availability, light intensity, CO2 concentration, temperature, and pH. There are various interesting reviews that have focused on different strategies to improve the growth and valuable compounds of microalgae, such as genetic engineering tools. However, recently, nanotechnology emerges as a field that offers novel and efficient methods to improve culturing conditions. To enhance the valuable compounds in microalgae, nanoparticles (NPs) with unique and different physiochemical behaviors are utilized and this review focuses on discussing and providing the state-of-the-art techniques that involve NPs and that are employed to improve microalgae growth rate, light utilization, access to carbon dioxide, and therefore increase the valuable compounds in microalgae cells.